Fuel injection pump



Sept. 25, 1951 J. DlcKsoN ETAL FUEL INJECTION PUMP 5 Sheets-Sheet l Filed Sept. 17, 1947r nq l Sept. 25, 1951 J. DlcKsoN ETAL FUEL INJECTION PUMP 5 Sheets-Sheet 3 Filed Sept. 17, 1947 f l; v). u. d y?. Vf

Sept. Z5, i951 J. mcKsoN ETAL 2,559,233 FUEL INJECTION PUMP Filed Sept. l?, 1947 5 Sheets-Sheet 4 Sept. 25, 1951 DlcKsoN ETAL 2,569,233

FUEL. INJECTION PUMP Filed Sept. 17, 1947 5' Sheets-Sheet 5 synssye/d 730.1/ dois #muy 917004100/ :inventor: c/Y @fifa/2 Y a Gttorncgs Patented Sept. 25, 1951 FUEL INJECTION PUMP John Dickson, Huntington Woods, and Kenneth L. Hulsing, Plymouth, Mich.; assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 17, 1947., Serial No. 774,636.

This invention relates to fluid actuated fuel Injection pumps. l

The principal object of the invention is to provide a simple fluid pressure actuated fuel injection pump in which metered quantities of fuel are injected directly into the actuating fluid at high pressure and including means to control movement of the parts and to insure exclusion of vapor and complete filling of the pump with fuel.

The construction by which the above and other objects and features of the invention are accomplished will become apparent by reference to the' following detailed description and `drawings il- Claims. (Cl. 10s-.41)

enlarged actuating piston portion .II adjacent the outer end having packing rings slidable in the end counterbore 5. A plunger retainer mechanism, generally indicated at I3, is detachably mounted in a groove adjacent the end of the plunger 9 for contact with the inner end face of the counterbore 1. The piston portion II of the reciprocating plunger 9 is closed by a cap member I'I secured to the outer end face of the piston portion I I.

A pump cylinder head I9 is `secured by means of cap screws 2| to the other end face of the cylinder Igto close the cylinder counterbore 1. A fuel metering plunger 23 is rotatable in an axial lustrating various modifications of the invention. l5 end opening in the head I9 and the inner end Figure 1 of the drawings is a longitudinal cross face thereof extends into and forms a fuel pumpsectional view of one modification of an injection ing chamber between the closed outer end of pump and mounting thereof with parts in secthe pumping plunger 9 and inner end of the tion and broken away. metering plunger 23. A lever 26 is secured to Figure 2 is an enlarged transverse sectional 20 theouterv end of the rotary plunger 23 foranview taken on line 2-2 of Figure 1 with parts guiar adjustment thereof. A helical compresbroken away and in section. sion spring 21 is placed between the pumping Figure 3 is an enlarged transverse sectional plunger retainer member I3 and the outer end view taken on line 3-3 of Figure 1 with parts of a cavity in the cylinder head I9 to normally broken away and in section. 25 urge the plunger outwardly of the cylinder on Figure 4 is a view similar to Figure 3 of a modithe inlet or filling stroke to increase the volume fled structure. of the pumping chamber 25 and move the re- Figure 5 is a diagrammatic developed view of tainer I3 into contact with the inner end face cooperating parts of the injection pump mechaof the cylinder counterbore l and retain the nism'in various relative positions in order tobet- 30 cuter or working face of the plunger piston porter 'explain the operation thereof.

Figure 6 is'a view similar to Figure 1 showing another modification of a fuel injection pump of simpler form and the mounting details thereof.

Figure 7 is an enlarged exploded view of certain of the parts shown in Figure 6.

Figure' is a view similar to Figures l and 6 showing a third modification of a fuel injection pump and the mounting details thereof.

Figure 9 is an enlarged view of certain of the parts shown in Figure 8 with parts broken away and in section;

Figure 10 is a view taken on line Ill-IIJ of Figure 9.

Figure 11 is a graph in which the gas pressure in the engine combustion chamber for actuating the injection pump and the fuel pressure in the pumping chamber of the pump are plotted against the crank angle of the engine.

As best illustrated in Figure 1 the fuel injection pump comprises a pump cylinder I having a longitudinal bore 3 with counterbored end portions 5-`l. A hollow reciprocating fuel pumping plunger 9 is shown having packing rings slidable in the cylinder bore 3 and is provided with an tion II flush with the other outer end face of the cylinder counterbore 5, as shown in Figure 1. A packing ring 29 is provided in an external groove in the head end of the cylinder I and a tapered exterior surface 3| is provided on the piston end of the cylinder so that the injection pump may be mounted in fluid tight relation in a bore 33 extending through an engine cylinder head 35'and having a tapered seat surface with a gasket 3l thereon on which the tapered surface 3l isV held by means of a stud 39 shown extending through a hole in the cylinder head I9 of the pump and threaded in an opening in the engine cylinder head 35, the external packing ring 29 of the pump cylinder then engages the inner surface of the engine cylinder head bore 33. fluid tight relation in the engine cylinder head 35 the working face of the pumping plunger piston portion Il is subjected to the pressure in the combustion chamber between the engine cylinder head 35 and working piston 4I.

Dametrically spaced longitudinally extending external grooves 43-43' are provided on thel pump cylinder I intermediate the ends thereof..

With the injection pump thus mounted in A counterbore I is provided in the groove 43 in which a filter 52 is placed and a passage 53 leads from the counterbore 45 to the pump cylinder bore. The inner end of a fuel supply passage 58 in the engine cylinder head- 35 opens into the groove I3 on the pump cylinder which serves as a fuel supply chamber 49 from which the fuel passes through the counterbore l5. filter 52 and passage 53'to the bore of the pump cylinder I. The fuel supply passage 50 in the engine cylinder head is supplied in conventional manner with fuel under pressure by a transfer pump, not shown. Another counterbore 45' in the groove 43' has another filter 52 therein anda return passage 53' leads from the cylinder bore to the counterbore 45'. The inner end of a fuel return passage 5| in the engine cylinder head 35 opens into the groove I3' serving as a fuel return chamber 49' and the excess fuel and any vapor therein is vented through the passage 53', counterbore I5', ter 52 and fuel return passage 5| in the engine cylinder head 35.

The fuel pumping plunger 9 is also provided with diametrically spaced longitudinally extending grooves 55-55'. The groove 55 serves as an inlet pressure supply groove as it registers with the inlet supply passage 53 in the pump cylinder I for all positions of the reciprocating fuel pumping plunger 9. The groove 55 of the fuel pumping plunger 9 serves as a fuel and vapor return groove as it registers with the fuel return passage 53 in the pump cylinder vI for all positions of the reciprocating fuel plunger 9. A fuel inlet and cutoff port 51 is provided in the fuel inlet groove 55 of the pumping plunger and a fuel return and vapor vent port 58 is provided in the fuel return groove 55 of the pumping plunger. The fuel inlet and cutoff port 51 and the fuel return and vapor vent port 58 normally register with an external fuel metering groove 59 provided on the `metering plunger 23 which is also provided with communicating axial and diametral passages/ 65-66 for establishing continuous communication between the fuel metering groove 59 and the fuel pumping chamber 25. The vent port 58 normally registers with the upper end of the metering groove 59 to insure proper venting of vapor therefrom. With this port and passage arrangement fuel is continuously circulated therethrough when the plungers are in the normal filling position, shown in Figure l, to insure complete iilling of these passages and the pumping chamber with filtered fuel and for venting vapor therefrom.

The fuel metering groove 59 is provided with axially spaced helical control edges 6|63 and adjacent axially spaced control edges 52-64 normal to the plunger axis, asbest shown in Figure 5, and the ports 51-58 move past the control edges 6|52 to cut olf fuel inlet to and fuel and vapor return from the pumping chamber when the pressure in the engine combustion chamber rises to a value suflicient to overcome the force of the plunger return spring 21. The fuel thus trapped in the pumping chamber 25 and plunger passages is then compressed and this retards movement of the pumping plunger on'the pumping stroke.

An internal recess 51 is formed in the piston portion of the pumping plunger 9 by drilling a hole radially therethrough and closing the outer end thereof by means of a plug 1|. The recess 51 serves as a pressure discharge passage and normally registers with the reduced diameter Y portion 10 of the metering plunger and, upon a given movement of the pumping plunger on'the pumping stroke, the recess overlaps the helical control edge 63 and the adjacent edge 59 of the reduced diameter outer end portion 18 nor-l mal to the axis of the rotary plunger 23 to permit delivery of the compressed fuel under high pressure from the pumping chamber 25 through this recess and the passages -56 to the space adjacent the reduced diameter end portion 18 thereof. As best illustrated in Figures 1 and 3 a check valve mechanism comprising an annular cap member 15 is pressed on the reduced diameter outer end portion 10 and this cap is slldable in the bore of the pumping plunger and forms an annular groove adjacent the inner end face of the rotary metering plunger 23. The cap member 15 is'provided with an outer end portion having an axial end opening 11 in alignment with the axial plunger passage 85 and an external annular groove 19, as best illustrated in Figure 3. The cap 15 has a pair of diametrically positioned conical seat passages 8|, having balls 83 adapted to seat therein. The seat passages 8| extend from the bottom of the external groove 19 in the cap 15 to axially extending grooves 85 provided in the reduced diameter end portion 19 of the metering plunger 23 to permit one-way delivery of fuel through the axial plunger grooves 85, seat openings 8| and past the balls 83 therein and through the external groove 19 of the cap member 15 and discharge ports 83' provided in the outer end of the hollow pumping plunger 9 when these ports register with the cap groove 19 so that fuel under pressure is discharged directly into the engine combustion chamber. The balls 83 in the seat openings 8| seat to prevent flow of iiuid pressure from the engine combustion chamber into the injector pump when,

the cap groove is in register with the discharge ports and the fluid in theengine combustion vchamber is greater than that of the fuel pressure in the pumping chamber 25 which occurs on the return or lling stroke of the pumping plunger.

The check valve structure shown in Figure 4 differs only from that shown in Figure 3 by the provision of three axial grooves 85' in the outer reduced diameter end portion of the rotary plunger 23' and three conical seat openings 8|' in the cap member 15 in which three balls are positioned to provide the same function but with less restriction to one-way fuel delivery therethrough.

In order to prevent rotation of the reciprocating plunger 9 and piston portion thereof a pin 81 is pressed in a longitudinal opening in the piston portion thereof and extends into a longitudinal passage 89 extending through the pump cylinder With the ports of the fuel pump in the normal filling position, as shown in Figure 1, and the rotary plunger 23 adjusted angularly to the maximum fuel delivery or full engine load position the relative angular and axial positions of the control edges 6|-62--B3-64-69 of the metering groove 59 of the metering plunger 23 and the ports 51-58-83, and internal recess 61 of the pumping plunger 9, are shown diagrammatically in Figure 5, by the line A connecting these ports and recess. By reference to Figure 11 it will be noted that about before top center TC, indicated at 0, the gas pressure in the combustion chamber exerts suiicient force on the working face of the pumping plunger piston portion to overcome the force of the return spring 21 `and move the plunger 9 inwardly on the metering plunger. and in the cylinder I on the discharge stroke todisplace fuel through the ports 61,-56

- metering plunger, as best seenon line B of Fig- 'ure 5 and indicated in Figure 1l as Start of FullLoad Overlapff displacement of fuel Vfrom the-'pumping chamber 254 is cut off and the fuel remaining therein is 'compressed which retards movement of thepumping plunger-by thesubsequent rapid increase lin gas pressure applied thereto, as indicatedin Figure "1 1 as Start of Control Delay Period. At about 25 before top center the pumping r'ilunge'rrecess61v moves into overlapping relation with thecontrol edge 63 and the adjacent 'edge 69 vof the reduced diameter portion 16 of the, metering plunger, and the groove `19 inthe .check valve ca'p 15 registers with the discharge openings'' in the` end of the pumping (plunger in-'theengine combustion chamber 'tocause Full LoadfStart of Injection"` as 'indicated in'Figure'l 1,.` The highly compressed fuel trapped; in thel 'pumping'chamber 25 will accordingly escape ,at'hi w through the passages. Ametering groove 59 of the metering plunger 23,through the pumping plunger recess 61' to the [space adjacent the reduced diameter portion vof the metering plunger and flow outwardly' through the grooves B5 thereon and past the balls 63 in the conical seat openings 81 to the groove 19 in the check valve cap and outwardlythrough the discharge openings 83' vinto the engine combustion chamber. It will be noted that the gas pressure in `the engine combustion chamber is rapidly increasing at the start of fuel injection and by proper selection of the number vand area of the discharge openings 83' the 'injection pressure' therethrough may be made constant or be made to increase or decrease as desired until the discharge openings 83 move out of register with the groove 19 in the'check valve cap to 'cause the "End ofLFuel Injection, shown on Figure 11, causingretrapping of the fuel in the pumping chambery and passages communicating therewith. This` causes retardation and end of further movement of the pumping -plunger by the combustion of the fuel-air mixture in the engine combustion chamber and a further rapid increase in the gas pressure therein,v not shown on the gas pressure curve, which showsonlyfc'ompression pressure and not combustion 1 pressure.' The trapped fuel is thus highly compressed and stops further movement of the pumping plunger even though combustion pressure acts thereon. This prevents metal to metal contact between the pis-v4 ton portion Il of the pumping plunger 9 and the end` face of the adjacent counterbore 5 of the pump cylinder I. When the pressure' in the combustion chamber falls due to expansion and exhaust of the gas therefrom, the plunger lreturn spring 21 returns the pumping plunger 6 to the normal position as shown in Figure l. During the return of the pumping punger 9` to the normal fuel filling position the registering of the jdscharge openings 83' therein with the groove 19 of the check valve cap 15 of the meterj ing plunger 23 causes the balls 83 to be seated on the conical seat openings 8| of the cap by the suction in the pumping chamber 25, due to the increase in volume thereof, thereby preventgas under greater pressure from the combusation chamber from being drawn into and mixing with the fuel inthe pumping chamber.

ressure therefrom f' As mentioned the helical control edges 6I-63 on the metering plunger 23 are inclined at the same angle to the axis or parallel to each other as shown bestr in Figure 5. It will accordingly be apparent by reference to Figure 5 that when the ports 51-58 and the recess 61 of the pumping plunger are in the full load position, shown on line B relative to the control edges 6 |-62-63-64 -of the metering plungerwith the ports 51-58 overlapping the control edges 6I-62, the trapped fuel in the pumping chamber and communicating ypassages. is compressedby movement of the pumping plunger necessary to causefthe recess 61 to be moved past the helical control edge. .An equal amount of pumpingplunger movement is required `to cause the recess 61 to be moved past a different portion of the helical control edge 63 when the ports and recess are in position C in Figure 5 with the ports 51 and 58 in overlapping relation with different portions of the control edges 6l--62 corresponding to the zero fuel delivery of kfuel from the pump to cause shut down of the engine.` When in position C the` recess 61 in moving past the helical control edge 63 simultaneously moves past the control edge 69 and accordingly does not overlap these edges and therefore no fuel is discharged into the engine combustion chamber. From the above it will be evident that the part load relative positions of the ports, recesses and control edges are between lines A and C in Figure 5 in which positions more fuel is displaced from and therefore less fuel is trapped in discharge from the pumping chamber than in the full load position; however the pumping plunger moves an equal amount to compress greater or lesser amount of fuel trapped prior tothe overlapping ofthe control edges 63-69 by the recess 61 to cause the start of fuel injection. The pressure of the compressed fuel at start of injection will accordingly be higher for the part load setting of the metering plunger than for the full load injection as trapping of the fuel occurs later in the discharge stroke of v`the pumping plunger' when the gas pressure in the engine combustion chamber acting on the' plunger is higher.' This is seen in Figure 1l by comparing the fuel pressure at the start of injection for parl; and full load setting of the metering plunger which as described is tion in the compression pressure of the enginev over ifs speed and load range are taken into consideration.

The fuel injection pump shown in Figure 6 is similar to that shown in Figure 1 exceptfor details which-provide controlled return movement of the pumping plunger on the filling stroke as well as on the discharge stroke and a check valve mechanism of simpler form is included in the v`pumping plunger instead of -on the metering plunger. The injection pump shown in Figure 6 inclu-des a cylinder IUI having a central bore |03 and end counterbores |05-I01. A hollow pumping plunger |09 having packing rings is-slidable 1 in the cylinder bore |03 and is provided with an enlarged piston portion also having packing rings slidable in the cylinder counterbore |05. A plunger retainer mechanism ||3 is threaded on the opposite end and is located in and provided with a packing ring slidable in the opposite end cylinder counterbore |01. A cylinder head I|9 is secured to the cylinder |0| by means similar to that shown in Figure 1. to close the outer end of the counterbore |01. A fuel metering plunger |23 is rotatable in the cylinder head ||9 and extends into the pumping plunger |09 to form a pumping chamber |25 adjacentl the piston portion thereof, which includes a check valve and fuel discharge passages opening into the engine combustion chamber which will be subsequently described. A helical compression spring |21 is placed between an annular mem- 11er |28 nonrotatably-engaging a square end p0rtion |29 of the pumping plunger and the plunger insure the escape of any vapor therefrom.

retainer member vIlil and the outer end of a l cavity in the cylinder head ||9 to urge the pumping plunger to the normally filling position shown. The member |28 is provided with a lug |28' slidable in a longitudinal keyway ||9' in the cylinder head ||9 to prevent rotation of the pumping plunger |09. The pump vcylinder is secured in fluid tight relation in the bore 33 extending through the engine cylinder head 35 in the same manner as described relative to the modication shown in Figure 1.

The cylinder is likewise providedwlthlongitudinally extending diametrically spaced external fuel pressure suply and return grooves ,|43-|43 having counterbores |45-I45 therein and including filter elements 52 and passages |53-|53 leading from each counterbore to the central bore |03 of the cylinder |0 The longitudinal grooves I43-I43 in the pump cylinder |0|, respectively, registering with the fuel supply and return openings 50--5I in the engine cylinder head 35.

The pumping plunger |09 is likewise provided with diametrically spaced longitudinally extending grooves |55-l55', respectively. registering with the fuel inlet and return passages` |53 and |53' in the pump cylinder |0| for all relative p0- sitions of the pumping plunger with respect thereto. A fuel inlet and cutoff port |51 is provided in the plunger groovey |55 and a fuel return and vapor vent port |58 is provided in the plunger groove |55.

The ports |51- |58 are shown in the norma! position registering with a metering groove |59 in the metering plunger |23 which is provided with diametral and axial passages |63|65 leading from the metering groove |59 to a pumping chamber |25 located between the inner end of the metering plunger |23 and a counterbore 4|24 in outer or working face of the plunger portion of the pumping plunger |09, in which counterbore is located a fuel discharge valve having discharge passages openingl into the engine combustion chamber which will be subsequently described. The metering groove |59 is of the same form as that shown in Figures l and and likewise includes axially spaced helical control edges |6||63 and control edges |62-I64 adjacent thereto normal to the plunger axis. As the ports and metering groove are arranged in similar manner to that described in pump shown in Figures 1 and 5, when the ports are in the normal filling position, fuel enters and fills the pumping chamber and excess fuel and any vapor will pass outwardly through the return ports and passages. It will be noted that the fuel and vapor vent port |58 is normally positioned, in a A similar internal recess |61 is likewise pro-- vided in the pumping plunger bore which normally registers with an annularv groove |10, one, edge |69 thereof forming another of the plunger` control edges. The recess |61 is likewise adapted to move into overlapping relation with the control edges |63|69 after the ports |51-|58 overlap the control edges ISI-|62 upon movement of the pumping plunger on the discharge stroke to permit the compressed fuel trapped in the pumping chamber and passages to enter the annular plunger groove |10.' The groove |10 at this timev registers `with another recess |1| and a passage |12 leading therefrom to the previously mentioned counterbore |24 in the piston portion of the pumping plunger |09. The recess |1| is normally closedy by the inner end of the pumping plunger, as shown in Figure 6, and when this end moves past the upper extremity of the plunger recess |61 discharge of fuel and the end of injection occurs and the remaining fuel in the pumping chamber |25 is again trapped to stop further movement of the pumping plunger by the increase in gas pressure in the engine combustion chamber due to combustion of the fuel therein, in the same manner as previously explained with reference to the pump shown in Figure 1. I

'I'he check valve mechanism shown in the counterbore |24 of the pumping plunger includes a valve seat |13 of disk form and a valve disk |14 adapted to seat thereon, as best shown in Figure 7. 'Ihe valve disk |14 is located in an axial recess |15 in the inner end face of a'fuel spray tip |16 contained in a threaded cap |11 which is threaded into the'counterbore |24 of the pumping plunger to draw the inner face of the spray tip into contact with an annular gasket |18 bearing on the outer face of the seat disk |13 which has a gasket |19 on theother face and this gasket is accordingly drawn into contact with the face ofthe pumping plunger counterbore |24. The disk seat |13 has a locating pin secured to and extending from the inner face through a hole |8| inthe gasket |19 and into a longitudinal opening in the pumping plunger. The gasket |19 and disk seat |13 have communicating passages |83|84 registering with the longitudinal discharge passage |12 of the pumping plunger. The passages |84 of the disk seat communicates by way of a diametral passage |05 with an axial opening |81 in the outer face of the seat disk adjacent the valve disk |14. The valve disk |14, as best shown in Figure 7, is provided with peripheral grooves |88 to permit discharge of fuel from the axial opening |81 in the seat disk through these slots and the axial recess |15 in the spray tip |16 to an axial passage |89 and communicating discharge passages |90 therein, which discharge passages open into the engine combustion chamber. With the above check valve mechanism in the working face of the pumping plunger it will be evident that the valve disk |14 will be seated on the outer face of the disk seat |13 and close the axial opening |81 therein when the pressure in the engine combustion chamber is greater than that in the fuel pumping chamber |25. This occurs when the pumping plunger is being returned by the spring |21 on the lling stroke and the annular groove |10 registers With the recess |1| communicating with the check valve mechanism. As

explained previously the operation of the above described injection pump shown in Figure 6 is identical with that shown in Figure l and previously described. The additional feature of the pump shown in Figure 6 is that when the end of fuel injection occurs the upper end of the longitudinal fuel pressure supply groove |55 of the pumping plunger is above the bottom of the counterbore |01 at the head end of the pump cylinder This causes fuel at supply pressure to fill the space in the counterbore |01 between the packing ring on the pumping plunger retainer mechanism ||3 and when the plunger is returned by the spring |21 the fuel trapped in the counterbore |01 below the plunger retainer, by movement of the upper edge of the groove |55 past the face of the counterbore |01, to retard and cushion return movement and prevent metal to metal contact between the plunger retainer and the faceof the counterbore |01. 'I'he trapped fuel in this space accordingly holds the pumping plunger retainer in spaced relation with the face of the counterbore when the plunger is in the normal filling position, as shown in Figure 6. The Return StopA Pressure" is indicated on the Normal Fuel Pressure curve in Figure l1.

The fuel injection pump shown in Figure 8 and its mounting in the engine cylinder head 35 is similar to those previously described and differs chieyA therefrom by including therein a different arrangement of discharge passages, a different check valve mechanism and not having the trapped fuel returnA stop feature for the pumping plunger. As best seen in Figure 8, the fuel pump cylinder and pumping plunger 209 are provided with similar fuel pressure supply and return passages. The metering plunger 223 is providedwitha metering groove 259 of the same form with which the ports 251-258 in the pumping plunger cooperate in the same manner as previously described. The metering plunger 223 is likewise rotatable in the pump cylinder head 2|9 which is secured in asimilar manner to the pump cylinder 20|.v The pumping plunger retainer mechanism 2|3 is similar to that shown in Figure 1 and a return spring 221 is placed between this retainer mechanism and the flange 228 of a hollow member 229. The flange 228 is in contact with the end of the cavity of the pump cylinder head 2|9 and a pin 230 therein extends through a hole in the flange to prevent rotation of the hollow member 229. The hollow member .is provided with a longitudinal slot 23| in which a projection 232 of the pumping plunger 209 slides to prevent rotation thereof. It will be noted that the piston portion 2|| of the pumping portion is provided with intersecting drilled vpassages'265-2l6 having their outer ends closed by means of plugs. The inner end of the passage 265 normally registers with the metering groove 259 and the inner end of the passage 266 opens into the fuel pumping chamber 225 adjacent the inner end of the metering plunger 223 by which fuel can enter to fill the pumping chamber and` for the fuel compressed therein to enter the metering groove, thus serving the same function as the passages 65-66 in the metering plunger 23 shown in `Figure 1 or similar metering plunger passages IE5-|66, as shown in Figure 6. The metering plunger 223 is provided with an annular groove 210 shown in Figures 8 and 9 registering with a recess 261 in the pumping plunger formed by a plugged hole and a longitudinal slot intersect-y ing the hole. This recess 261 serves the same purpose as the recesses 61 and |61 shown in Figures 1 and 6, namely, to overlap the helical control edge 263 of the metering groove 259 vand the adjacent control edge 269 of the annular groove 210 of the metering plunger to allow passage of compressed fuel from the pumping chamber to enter the groove 210. As best seen in Figure 9 a diametrical passage 21| and an axial passage 212 leads from the groove 210 to the inner end face of the metering plunger and a plug 23| closes the end of the axial passage. Another annular groove 219 is provided in the metering plunger between the inner end face and the groove 210. Radial holes 28| lead from the bottom of the groove 219 and the axial passage, as best shown in Figure 10, and a split ring 293 serves as a check valve to permit fuel under pressure to escape through the holes 28|. The groove 219 is positioned to register with the discharge passages 283' in the outer or working face of the pumping plunger when the recess 261 overlaps the control edges 263-269 to cause discharge of fuel through the discharge openings 283' into the engine combustion chamber. It will be seen that this valve structure and passages therewith is similar to that described with reference to that shown in Figure 1 and serves the same purpose.

The three modifications of pressure operated fuel injection pumps disclosed enables accurately amounts of pre-compressed fuel to be injected per discharged stroke at proper pressure for full and part load operation of an internal combustion engine in the manner described and the movements of theA pressure operated pumping plunger to be controlled thereby overcoming the shortcomings of mechanically operated pumps in whichv the injection-pressure is proportional to the velocity of movement of the additional mechanical operating means required, which is engine driven.

We claim: s

1. A fuel injection pump comprising a cylinder, a pair of telescopically disposed plungers therein, spring means normallypositioning the plungers in spaced relation to form a fuel pumping chamber therebetween, one plunger being movable by fluid pressure in the cylinder toward the other plunger against the action of the spring means on a fuel discharge stroke, said cylinder having fuel inlet and return passages, said plungers having fuel inlet, return and discharge passages, the fuel inlet and return passages of the cylinder and plungers registering when the movable plunger is moved. by the spring means to the normal position in order to completely fill these passages. and the pumping chamber with fuel, said movable plunger upon movement in the first part of the discharge stroke cutting off communicationof the cylinder fuel inlet and return passages `with the pumping chamber and thereby trapping and compressing the fuel therein and further movement of the movable plunger on the fuel discharge stroke y establishing momentary communication between the pumping chamber and the plunger inlet, return and discharge passages thereby causing momentary dischargev of compressed fuel from the pumping chamber and retrapping and compressing the remaining fuel therein to stop flu-ther movement of the plunger on the discharge stroke.

2. A fluid pressure actuated fuel injection pump comprising a cylinder, a pair of plungers telescopically arranged therein, one plunger being acll tuated by fluid pressure applied thereto on the fuel discharge stroke relative to the cylinder and other plunger, engageable stop means on the cylinder and movable plunger, spring means causing engagement of the stop means to normally position the movable plunger at the end of the fuel filling stroke in spaced relation with the other plunger to form a fuel pumping chamber therebetween, said cylinder and plungers having fuel inlet and return passages registering only when the movable plunger is atthe end of the fuel inlet stroke to cause fuel filling of the pumping chamber and venting of vapor therefrom. said plungers also having pressure discharge passages communicating with the first mentioned plunger passages and registering momentarily only when the movable plunger is pressure actuated on the pressure discharge stroke to cause momentary discharge of fuel from the pumping chamber andto trap and compress the remaining fuel therein to stop further movement of the movable plunger on the discharge stroke.

3. A fuel injection pump comprising a cylinder having fuel inlet and return passages therein, a

pair of telescopically arranged plungers in the cylinder, one of said plungers being fluid pressure movable in said cylinder toward the other plunger on a fuel discharge stroke, means including a spring for returning the movable plunger to and normally positioning the movable plunger in a fuel filling position spaced from the other plunger to form a fuel pumping chamber between the plungers. said plungers having fuel inlet and return ports. passages and grooves normally positioned by the spring to cause complete filling of the pumping chamber with fuel, at least one of said plungers having a groove with helical control edges angularly adjustable with the ports of the other plunger to vary the point cut off inlet and return fuel from the pumping chamber upon movement of the movable plunger on the start of fuel discharge stroke to trap and compress the fuel in the chamber, said plungers also having fuel discharge grooves and passages registering momentarily with certain of the fuel inlet and return plunger passages and grooves when the movable plunger is near the end of the fuel discharge stroke to control momentary discharge of the compressed fuel from and to retrap and compress fuel inthe pumping chamber and thereby limit further movement of the movable plunger on the fuel discharge stroke.

4. A fluid pressure actuated fuel injection pump comprising a cylinder, `a pair of telescopically arranged plungers therein. one plunger being adjustable angularly in said cylinder and the other being movable axially toward said angularly adjustable plunger and into said cylinder on the fuel discharge stroke by fluid pressure acting on the outer face thereof, means including a spring for normally positioning said axially movable plunger spaced from said angularly adjustable plunger to form a fuel'chamber therebetween, said cylinder having fuel inlet and return passages and said plungers having fuel inlet and return vand fuel discharge grooves. passages, ports and recesses normally positioned to cause complete filling of said chamber and plunger passages with fuel, at least one plunger groove having inclined edges, one edge of which certain ports of said other plunger overlap on the rst part of the discharge stroke to vary the cut olf of inlet and return fuel from said chamber. depending upon the angular adjustment of said angularly adjustable plunger. to trap and cause compression of the fuel in said chamber and thereby retard compression movement of said axially movable plunger. certain other of said plunger discharge ports, recesses and grooves momentarily overlapping the other helical edge of said plunger groove during the latter part of the plunger discharge stroke for causing momentary fuel discharge of the compressed fuel from said chamber and cut olf of fuel discharge to again trap and compress the fuel remaining in said chamber and thereby retard and stop further movement of said axially movable plunger on the discharge stroke.

5. A fluid actuated fuel injection pump comprising a cylinder, a pair of plungers telescopically arranged therein, one plunger being movable on the fuel discharge stroke toward the other and into the cylinder by fluid pressure acting thereon, means between said cylinder and 'said movable plunger including a spring for normally retaining said plunger spaced from the other to form a fuel chamber therebetween, said cylinder and said plungers having cooperating fuel inlet and return passages normally retained to insure complete filling of said chamber with fuel and the return of excess fuel and any vapor therefrom, and for cutting off fuel therefrom to cause compression of the fuel therein and retardation of plunger movement during the first part of the plunger discharge stroke said plungers having other cooperating passages registering momentarily during thelatter part of the discharge stroke to cause momentary discharge of the compressed fuel from and recompression of the remaining fuel in said chamber to stop further movement of said movable plunger at which point in the plunger discharge stroke the plunger, the plunger and the cylinder inlet fuel passage registers with the space between said plunger, plunger retaining means and said cylinder to fill this space with fuel which is compressed upon the return of said plunger by said spring to the normal position to prevent impact between said means and said cylinder.

6. A pressure actuated fuel injection pump for an internal combustion engine having a combustion chamber and a passage opening therein,

' a pump cylinder in said passage, a pair of telescopically arranged plungers in said cylinder, one of said plungers being rotatable in said cylinder to serve as a fuel metering plunger, said other plunger being movable axially toward said metering plunger and into said cylinder by the pressure in the engine combustion chamber, means for normally retaining said pressure movable plunger in spaced relation with said metering plunger to form a fuel chamber. spring means urging said pressure operated plunger into the l normally spaced relation, said cylinder having fuel supply and return passages, said metering plunger having a fuel metering groove with helical edges, passages communicating with said groove and said chamber and a reduced diameter portion having edges normal to the plunger axis. said pressure operated plunger having fuel inlet and return slots in continuous communication with the inlet and return cylinder passages, inlet and return ports in said slots normally registering with said metering groove to cause filling of said chamber with fuel and movable into overlapping relation 'with one helical edge of said metering groove to trap and compress the fuel in said fuel chamber during the first part of movement of said pressure movable plunger and thereby retard such movement, a recess in said pressure operated plunger, and a fuel discharge passage opening into the engine combustion cham- 13 ber movable into momentary register with said metering groove and reduced diameter portion of said metering plunger upon further movement of said pressure operated plunger for causing momentary discharge of the compressed fuel directly into the engine combustion chamber and for stopping discharge to retrap and compress the fuel remaining` in said fuel chamber and thereby stop further movement of saidv pressure operated plunger.-

7. In a fuel injection pump, a cylinder having a bore and fuel inlet and return passages communicating therewith, a metering plunger supported on said cylinder and extending into said bore, said plunger having an external metering groove intermediatethe ends and passages leading therefrom to the inner end face to serve as a fuel filling and fuel discharge groove and an external fuel discharge groove adjacent the inner end and a discharge passage leading therefrom to the periphery of the end portion adjacent the inner end face, a hollow pumping plunger slidable in said bore and on said metering plunger, said pumping plunger having a closed outer end projecting outwardly of said bore to form a fuel pumping chamber adjacent the inner end face of said metering plunger, the outer end face of the pumping plunger serving as an actuating piston portion, means normally urging said pumping plunger outwardly of said bore and metering plunger to a fuel filling position, said pumping plunger having an inlet port normally registering with said metering groove and with said cylinder fuel passages, an internal cavity normally registering with said fuel discharge groove and fuel discharge port normally covered by the peripheral portion of said metering plunger adjacent the inner end face to cause filling of the pumping chamber with fuel, said pumping plunger being moved inwardly of said bore andV metering plunger on the fuel discharge stroke by an increase in pressure on the actuating piston portion to initially cause closure of said inlet port to then cause said internal cavity to register with both of said grooves and said discharge port to register with said discharge passage to control the start of fuel discharge through said discharge port and to finally cause closure of said discharge port to stop fuel discharge therethrough and thereby limit further inward movement of said pumping plunger on the discharge stroke.

8. lin a fuel injection pump, a cylinder having aligned bores and fuel inlet and return passages communicating therewith, a fuel metering plunger rotatably supported on said cylinder and extending into said bores, said plunger having an external metering groove intermediate the ends, said groove having edges similarly inclined to the plunger axis, passages leading from said groove to the inner end face, and a pair of annular fuel discharge grooves axially spaced adjacent said face and a discharge passage therebetween, a hollow fuel pumping plunger having an intermediate actuating piston portion and a hollow stem slidable in said cylinder bores and on said metering plunger and a closed outer end to form a fuel pumping chamber adjacent the inner end face of said metering plunger, resilient means urging said pumping plunger outwardly of said bores to a fuel filling position, said hollow plunger having a fuel inlet port normally registering with said cylinder fuel passages and with said inclined edged plunger metering groove, an internal cavity normally registering with the innermost discharge plunger groove. and discharge ports normally covered by the periphery of said metering plunger adjacent the inner end face to cause complete filling of the pumping chamber with fuel, said pumping plunger being movable inwardly of said cylinder against the action of said resilient means by an increase in pressure on the outer end face of said plunger and plunger piston portion for initially causing movement of said inlet port past the inner inclined edge of said inclined edged groove to stop displacement of fuel through said port from and to trap fuel in said chamber and retard inward movement of said pumping plunger and to finally cause said internal cavity to overlap the outer inclined edge of said metering groove and the adjacent edge of the innermost annular discharge groove and to cause momentary registration of said discharge ports with said outermost annular discharge groove for causing momentary fuel discharge from said chamber and for stopping further inwardly movement of said pumping plunger when discharge ends, and means for rotating said metering plunger to vary the point of closure of said fuel inlet port subsequent to overlapping action of said recess in order to vary the amount of fuel discharged per stroke.

9. In a fuel injection pump, a cylinder having aligned bores and fuel inlet and return passages communicating therewith, a fuel metering plunger rotatable on said cylinder and extending axially into said bores. said plunger having a combined fuel inlet and return exterior groove provided with similar helical edge portions axially spaced apart. a pair of annular discharge grooves axially spaced apart adjacent the inner end face, a discharge passage between said discharge grooves, a one-way discharge valve in said passage, a hollow pumping plunger having an intermediate actuating piston reciprocal in said cylinder bores and on said metering plunger and having a closed outer end forming a fuel pumping space adjacent the inner end face of said pumping plunger, a spring and retaining means for normally urging and retaining said pumping plunger outwardly of said cylinder and said metering plunger in a filling position, said pumping plunger having a fuel inlet and return port registering continuously with said cylinder fuel passages and normally registering with said plunger fuel inlet and return groove, an internal recess normally registering with the innermost annular plunger discharge groove and discharge ports spaced axially outwardly from said piston portion and normally closed by the peripheral end surface adjacent the end face of said metering plunger, said pumping plunger being moved inwardly on the fuel discharge stroke by an increase on the outer end surfaces suiiicient to overcome the forceof said spring to initially cause said inlet and return port to move past the helical edged fuel inlet and return groove and to trap a preselected volume of fuel in said pumping chamber and plunger passages and thereby retard inward movement of said pumping plunger and thereafter to cause said plunger internal recess to register with both said plunger inclined edged groove and said adjacent discharge groove and said plunger discharge ports to register momentarily with said other plunger discharge groove and cause momentary one-way discharge of fuel from said ports, further inward movement of said pumping plunger on the discharge stroke being then stopped by the fuel trapped in said pumping chamber after momentary discharge therefrom.

10. In a fuel injection pump. a cylinder having 15 aligned bores and fuel inlet and return passages communicating therewith, a cylinder head secured to said cylinder, a fuel metering plunger adjustable angularly in said head and extending axially into said cylinder bores, said plunger having a circumferential groove intermediate its ends, said groove having axially spaced control edges normal to the plunger axis and control edges inclined outwardly at the same angle therefrom, passages from said groove to the inner end face, a pair of annular grooves adjacent said end face and a passage including a one-way valve between said pair of annular grooves, a hollow pump plunger having an actuating piston reciprocal in said cylinder bores and on said metering plunger and a closed outer end forming a fuel pumping chamber adjacent the inner end face of said pumping plunger, stop means on said pumping plunger, a spring between said cylinder head and stop means for normally moving said plunger outwardly of said bore and metering plunger to a lling position so that said stop means engages said cylinder, said pumping plunger having a reduced external diameter portion in continuous register with said cylinder fuel passages. a vent port and an inlet port axially and circumferentially spaced apart in said reduced diameter plunger portion and normally registering with said circumferential plunger groove, said vent port beingpositioned axially between the control edges of said circumferential groove normal to the axis and said inlet port being positioned between said inclined edges of said groove, an internal recess normally registering with said innermost annular groove, and discharge ports outside said plunger portion and normally closed by the periphery of said pumping plunger adjacent the inner end face forming the inner boundary of said pumping chamber to completely lll said chamber and communicating plunger and cylinder passages with fuel and to vent any vapor therefrom,said pumping plunger being inwardly movable with respect to said cylinder and metering plunger by pressure on the outer surfaces necessary to overcome the action of said spring to cause movement of said vent port past the inner edge of said circumferential groove normal to the axis, to then cause movement of said inlet port past said inner inclined edge of said groove to trap a predetermined amount of fuel in said pumping chamber and plunger passages depending upon the angular adjustment of said metering plunger, to then cause said internal recess to overlap the outermost inclined edge of said circumferential groove and the adjacent edge of said innermost annular discharge groove, and to finally cause said discharge ports to register momentarily with said outermost discharge groove to cause momentary one-way discharge of fuel through said ports. the fuel trapped in said pumping chamber and plunger passages by passage of said discharge ports past said outermost discharge groove stops further movement of said pumping plunger on said discharge stroke.

JOHN DICKSON. KENNETH L. HULSING.

REFERENCES CITED UNITED STATES PATENTS 5 Number Name Date 2,385,239 Unsworth Sept. 18, 1945 2,389,492 Edwards Nov. 20, 1945 2,430,801 Bremser Nov. 11, 1947 

